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Topic: Ethernet Shield & Mega (Read 58 times) previous topic - next topic

eSietsema

I've read the new R3 Ethernet Shields are 100% compatible with the new Mega units. My question is, are all the Mega digital pins available to use as inputs or just the pins directly connected to the Ethernet Shield? I am aware a handful of pins are used to communicate between the 2 boards.

Nick_Pyner

#1
Jun 16, 2016, 01:43 am Last Edit: Jun 16, 2016, 04:49 am by Nick_Pyner
The pins not used by the shield are pass-through and still available to you.

eSietsema

I'm assuming what your saying is that most all of the Mega's pins will be passed through and accessible. I was thinking that would be the case, or there would be no point in using a Mega with the Ethernet Shield. Thanks for the information!

BillHo

All MEGA pins are available except

D2     INT
D4     SD_CS
D10   SS
D50   MISO
D51   MOSI
D52   SCK

Nick_Pyner

#4
Jun 16, 2016, 05:45 am Last Edit: Jun 16, 2016, 05:47 am by Nick_Pyner
I'm assuming what your saying is that most all of the Mega's pins will be passed through and accessible.
Yes, I didn't realise how slack my typing was.  Indeed I submit that what BillHo has said is nonsense. The only pins I am aware of that you cannot use are
 D4, which is Select for the SD (if there is one)
D10, which is Select for ethernet
and therefore out of the game for general i/o

D2 is not connected, and not normally involved with either but it may be used if a solder bridge is placed across the "INT" pads to connect it to the W5100's INT pin. I have no idea why anybody would want to do this and such a caper is not supported by the Ethernet library, so if you never knew this, you didn't miss a thing.
 
D50>52 is the Mega SPI bus, but it is what it is, a bus. While the shield uses the bus for both Ethjernet and SD via the 6-pin ICSP cluster, thereby making it compatible with both Uno and Mega, it does not preclude the use of pins 50>52. A case in point is where you may have an SD card on some other shield, like a Mega TFT display.

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